Influence of Chemical Composition and Domain Morphology of Li2MnO3 on Battery Properties
Influence of Chemical Composition and Domain Morphology of Li2MnO3 on Battery Properties
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Li2MnO3化学成分和畴形貌对电池性能的影响
DOI：
10.1002/batt.202000251
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发表时间：
2020
影响因子：
5.7
通讯作者：
Kanno Ryoji
中科院分区：
文献类型：
--
作者：
Hikima Kazuhiro;Taminato Sou;Hinuma Yoyo;Shimizu Keisuke;Suzuki Kota;Hirayama Masaaki;Yasuno Satoshi;Tamura Kazuhisa;Kanno Ryoji
使用液体电池中的模型电极研究了具有层状岩盐（O3）结构的Li 2 MnO 3的反应机制，即电化学循环期间发生的变化。采用脉冲激光沉积法制备了厚度为30 nm、不同Li/Mn原子比和不同形貌的Li 2 MnO 3（001）外延薄膜。这些电极的充放电容量范围为150至300 mAh g-1，根据组成和形态的不同，具有不同的降解特征。 具有标称（Li/Mn原子比=2.07）和富Li（Li/Mn比=2.28）的膜在至4.8V的第一次循环期间经历不可逆的结构转变为活化相，而与晶粒尺寸无关。 活化后的层间距增加，这可能是过渡到O 1堆叠结构的结果。Li层和过渡金属层八面体在O 1结构中共享面，因此Li扩散将更容易，并因此导致考虑到O 1结构的活化。标称薄膜中的进一步降解较慢，但原因无法明确归因于成分或晶粒尺寸。离位X射线光电子能谱（HAXPES）结果表明，在充电过程中，一些O被氧化，而另一些则没有。由于高Li浓度，富Li膜显示出与固体电解质界面层的大的相互作用。
The reaction mechanism, which is the changes that happen during electrochemical cycling, in Li2MnO3with a layered rock‐salt (O3) structure was examined using model electrodes in a liquid battery. Epitaxial films of Li2MnO3(001) with thickness of 30 nm, various Li/Mn atomic ratios, and different morphologies were fabricated by pulsed laser deposition. These electrodes showed charge–discharge capacity ranging from 150 to 300 mAh g−1, with different degradation characteristics depending on the composition and morphology. Films with nominal (Li/Mn atomic ratio=2.07) and Li‐rich (Li/Mn ratio=2.28) underwent irreversible structural transformation to an activated phase, regardless of the grain size, during the first cycling to 4.8 V. The interlayer spacing increased after activation, which may be a result of a transition to a O1 stacking structure. Li layer and transition metal layer octahedra share faces in the O1 structure, hence, Li diffusion would be easier and therefore results in activation considered to the O1 structure. Further degradation was slower in the nominal film, but the reason cannot be clearly ascribed to composition or grain size.Ex situhard X‐ray photoelectron spectroscopy (HAXPES) results suggest that some O were oxidized but others were not during charge. The Li‐rich film showed large interactions with a solid‐electrolyte interface layer by virtue of the high Li concentration.